BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Nonlinear Quasinormal Modes in the Ringdown of GW250114: Observati
 onal Evidence for Nonlinear Gravitational Waves
DTSTART;VALUE=DATE-TIME:20261107T073000Z
DTEND;VALUE=DATE-TIME:20261107T080000Z
DTSTAMP;VALUE=DATE-TIME:20261023T162336Z
UID:indico-contribution-2975@indico.itp.ac.cn
DESCRIPTION:Speakers: Yifan Wang ()\nThe ringdown signal following a binar
 y black hole merger offers a crucial avenue for investigating black hole p
 roperties and testing General Relativity in strong-field regimes. Beyond l
 inear quasinormal modes\, General Relativity predicts the existence of sec
 ond-order quasinormal modes arising from the nonlinear coupling of gravita
 tional waves. This talk presents an analysis of the ringdown signal from t
 he gravitational-wave event GW250114\, demonstrating observational evidenc
 e for second-order quasinormal modes. Through a systematic calculation of 
 coupling coefficients for the first ten second-order modes\, and the appli
 cation of a novel data analysis method\, we find a Bayes factor of 62 supp
 orting the presence of these nonlinear modes at a selected ringdown starti
 ng time. A zero-amplitude hypothesis is excluded with a significance of 3.
 4 sigma\, and the inferred amplitudes and complex frequencies are consiste
 nt with General Relativity predictions. We will discuss the analysis metho
 dology\, key results\, and their physical implications\, illustrating how 
 black hole spectroscopy can be extended into the nonlinear regime and prov
 iding a new observational window for testing the nonlinear structure of Ge
 neral Relativity.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2975
 /
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2975/
END:VEVENT
END:VCALENDAR